STROKE

Vascular System Reminder: All brain function is dependent on oxygen. There are two main arterial supplies to the brain: –Carotid Arteries –Basilar Artery (comes off of vertebral arteries)

Identify the following arteries in the cerebral angiogram in the image above: Vertebral Artery - Basilar Artery Vertebal Arteries/Basilar Artery

Right Internal Carotid Artery

Stroke Reduction in or disruption of Blood Flow to the brain Two major categories: –Ischemic (blockage of artery) –Hemorrhagic (damage or tear in artery)

A side category: TIA or Transient Ischemic Attack. Typically involves small emboli in an artery that resolves rapidly. Thus, the physical or cognitive effects typically resolve within an hour to 24 hours. There is rarely persistent damage following a TIA TIAs are often a signal of an impending stroke.

Mechanisms of Brain Damage Excitotoxic Cell Death –Via excitatory amino acid release –Excess calcium flow –Free-radical release, etc. PARP (enzyme involved in cell repair via ATP turnover) – excess ATP turnover – cell death. Pnumbra (excess damage or halo surrounding vascular damage).

“Stroke” Often viewed as motor and speech phemomenon – due to the prevalence of middle cerebral artery stroke. Stroke can occur in any location and symptoms will map onto the brain region that has undergone O2 deprivation.

Medical Issue Physical Deficits rather than cognitive deficits attract the most attention after stroke. Physical rehabilitation is readily prescribed % of stroke patients have persistent cognitive impairments after stroke.

Clinical Issues to Resolve Obviously, the cognitive problems associated with stroke are going to vary in relation to the region. Damage to certain cortical targets may generate notable cognitive signs: amnesia, alexia, agraphia, apraxia, agnosia, etc. These signs often exist alongside “non-cognitive” signs such as emotional instability or loss of initiative. There is often depression following stroke. It is difficult to disentangle the axis of depression from that of cognitive dysfunction.

Vascular Dementia or Multi-Infarct Dementia Accumulated Cortical Infarcts Distributed across cortical networks Strategic Subcortical Infarcts –Generally disconnect the prefrontal cortex from the thalamus or basal ganglia (thalamus + BG and/or genu of internal capsule, etc. Cortical disconnection syndrome –Often white matter lesions (associated with hypofunction of cortical regions as well).

The Classic Case of the Rt. MCA

CONCLUSION Vascular incidents must be carefully followed, to prevent recurrence. Multiple vascular events may result in a dementia complex. Both physical and occupational/cognitive therapy are important in promoting remapping following stroke.